1. Technical Field
The present invention relates to an atomic cell manufacturing method, an atomic cell, a quantum interference device, an atomic oscillator, an electronic device, and a moving object.
2. Related Art
As an oscillator having a highly accurate oscillation characteristic over a long term, an atomic oscillator that oscillates based on energy transfer of atoms of an alkaline metal such as rubidium or cesium is known.
Generally, an operation principle of the atomic oscillator is divided into a method using a double resonance phenomenon using light and microwaves, and a method using coherent population trapping (CPT) using two types of lights having different wavelengths. Any type of atomic oscillator includes an atomic cell (a gas cell) in which an alkaline metal is sealed (for example, see JP-A-2013-38382).
In order to realize miniaturization in accordance with a recent demand for miniaturization of an atomic oscillator (particularly, a CPT-type atomic oscillator), an atomic cell having a structure in which a plurality of substrates are laminated is known. For example, in JP-A-2013-38382, when manufacturing such an atomic cell, two materials, which are obtained by bonding a glass substrate to one surface of a substrate on which a through hole passing through in the thickness direction is formed, are prepared, alkaline metals are disposed on the surface of the through hole of the glass substrate of one of the materials, and then the two materials are bonded to each other so as to seal the alkaline metal, thereby forming an inner space.
Here, typically, in the atomic cell, a large amount of the alkaline metals are sealed since a decrease in the amount of the alkaline metal over time is expected, and the surplus alkaline metals exist as liquid or solid materials.
However, in the atomic cell disclosed in JP-A-2013-38382, a large amount of the surplus alkaline metals exist on an area of the glass substrate through which light being applied to the alkaline metal transmits, and thus an amount of light transmission is reduced, and the characteristics of the light is deteriorated due to a portion of the light acting on the liquid or solid alkaline metal. For example, in the CPT-type atomic oscillator, an EIT signal which is a rapid signal generated in accordance with an electromagnetically induced transparency (EIT) phenomenon is used as a reference signal, but in the atomic cell disclosed in JP-A-2013-38382, the intensity of the EIT signal is small and thereby frequency stability is deteriorated.